1. Field of the Invention
The present invention relates to a manufacturing method of an image-forming apparatus, and particularly relates to a manufacturing method of an image-forming apparatus of a flat type in which an anode substrate and a cathode substrate are opposed to each other.
2. Related Background Art
In recent years, an image-forming apparatus of a flat type constructed by an anode and a cathode has been widely researched and developed. For example, an electron source used in this image-forming apparatus includes one that is constructed by a field emitter, a surface conduction electron-emitting device, etc. One example using the former field emitter is proposed in U.S. Pat. No. 4,884,010. One example using the latter surface conduction electron-emitting device is proposed in U.S. Pat. No. 5,066,883.
These devices differ from each other in the structure of an electron source, a driving method, etc. However, common features of these devices are that electrons are emitted from the cathode constructed by the electron source with plural electron-emitting devices being arranged, and the anode opposed to the cathode is arranged. This anode has a phosphor and electrons accelerated by an anode voltage are irradiated to the phosphor so that light is emitted from the phosphor and an image is formed.
The distance between this cathode and the anode approximately ranges from several hundred xcexcm to several mm. The interior of the image-forming apparatus is held in a vacuum. An electric potential of the anode is held approximately with several kilovolts to several tens of kilovolts to obtain luminance by emitting light using the irradiation of an electron beam. An isolation voltage in this portion is secured by a vacuum or an insulator, etc.
In the above image-forming apparatus, when an image is generally formed for a long time by stably emitting electrons, there is a case in which a vacuum arc discharge is observed. An electric current of this abnormal discharge is very large and ranges from several A (ampere) to several hundred A. It is considered that such an abnormal discharge is caused by an insufficient vacuum between the cathode and the anode, an electrode shape, or results of the generation of an abnormal electric field caused by a triple point of a vacuum, an electrode (metal) and an insulating substance.
When such an abnormal discharge is caused once, an electric current is concentrated into this discharge portion and there is a case in which anode and cathode portions are damaged. For example, this vacuum arc discharge causes a large electric current as a result and there is a case in which the electron-emitting device in the cathode is broken by a large amount of Joule heat due to this electric current. The electric potential of wiring for the cathode and connection is unstabilized by the concentration of the electric current. As a result, there is a case in which a device connected through the wiring is damaged.
A technique for arranging a resistor portion in the anode portion is conventionally disclosed in Japanese Patent Application Laid-Open No. 10-134740 to restrain the generation of such a vacuum arc discharge.
A manufacturing method of an image-forming apparatus in the present invention has the following processes.
Namely, a manufacturing method of an image-forming apparatus having a cathode substrate and an anode substrate opposed to each other is characterized by comprising:
a first setting process for setting the electric potential of an anode electrode formed on the anode substrate to a first electric potential; and
a second setting process for setting the electric potential of one portion of the anode electrode to a second electric potential.
The present invention is also characterized in that the anode electrode has a gap in one portion thereof.
The present invention is also characterized in that the anode electrode is constructed by plural anode electrodes and a gap portion is arranged between the anode electrodes.
The present invention is also characterized in that the first and second setting processes are respectively repeated plural times.
The present invention is also characterized in that the cathode substrate has a surface conduction electron-emitting device.